<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <script src="js/flexible.js"></script>
    <style>
        div {
            width: 2rem;
            height: 2rem;
            background-color: lightblue;
        }
    </style>
</head>

<body>
    <div></div>
</body>

</html>